1. Field of the Invention
The present invention relates to a workpiece attracting device having suction pads for attracting and carrying a workpiece.
2. Description of the Prior Art
Various suction pads have heretofore been used to attract and carry workpieces. One example is a bellows-shaped suction pad for attracting workpieces having a curved surface such as glass plates for liquid crystal display units, CRTs, etc.
FIG. 5 of the accompanying drawings shows a conventional workpiece attracting device having bellows-shaped suction pads. As shown in FIG. 5, the conventional workpiece attracting device, generally denoted at 1, comprises a block 2 having a thickness S, and a plurality of bellows-shaped suction pads 5 mounted respectively in holes 4 in the block 2 by respective attachments 3. The workpiece attracting device 1 serves to attract and carry a glass plate 6 having a curved surface.
The bellows-shaped suction pads 5, which will be brought into direct contact with the glass plate 6, are made of rubber, and each have a suction port 7 which is held in communication with a suction passage 8 defined in the block 2 through the attachment 3.
Since the bellows-shaped suction pads 5 are made of rubber, an oily substance oozing from the bellows-shaped suction pads 5 tends to stick to the surface of the glass plate 6, leaving pad marks on the glass plate 6 which tend to lower the quality of the glass plate 6.
When the glass plate 6 is attracted by the workpiece attracting device 1 immediately after the glass plate 6 is removed from a furnace and hence has a high temperature of about 200.degree. C., the bellows-shaped suction pads 5 that are in contact with the glass plate 6 are subjected to a chemical reaction and generate gases which are liable to adversely affect the surrounding environment.
Furthermore, the thickness S of the workpiece attracting device 1 is relatively large, causing the workpiece attracting device 1 to take up a relatively large space. Consequently, demands to effectively utilize more space around the workpiece attracting device 1 cannot be met.